A One Health genomic assessment of Salmonella enterica across dairy, poultry, and environmental reservoirs in British Columbia, Canada

Salmonella enterica is an important zoonotic pathogen affecting animal and human health. Using a One Health approach, we conducted a comparative genomic analysis of S. enterica recovered within a restricted peri-urban region in Western Canada consisting of six dairy farms, an organic poultry farm, surrounding environments, and municipal wastewater. Overall, Salmonella prevalence was low, with 34 of 1,004 samples (3.4%) testing positive and representing 11 serovars. Antimicrobial resistance was limited: all isolates were susceptible to 12 of 14 antimicrobials tested, with resistance detected only to streptomycin (35%) and tetracycline (12%). Although all isolates carried the cryptic aminoglycoside resistance gene aac(6')-Iaa and 65% harboured the parC T57S mutation, neither determinant was associated with phenotypic resistance. Serovar Kentucky was the most widely distributed, occurring in dairy, poultry, and environmental samples. Plasmid profiles indicated genomic linkages among isolates from dairy farms, poultry, and the environment. Phylogenomic analyses revealed genetic similarities across animal and environmental sectors, while comparison with publicly available S. enterica ser.Enteritidis genomes identified a potential linkages between poultry and dairy production systems. These findings highlight the low prevalence of Salmonella in the study region and the value of One Health surveillance for identifying reservoirs, transmission pathways, and opportunities to strengthen biosecurity.